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From: Alex Elder <aelder@sgi.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 3/6] xfs: introduce inode cluster buffer trylocks for xfs_iflush
Date: Fri, 25 Mar 2011 16:00:50 -0500	[thread overview]
Message-ID: <1301086850.2537.681.camel@doink> (raw)
In-Reply-To: <1300860870-15471-4-git-send-email-david@fromorbit.com>

On Wed, 2011-03-23 at 17:14 +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
> 
> There is an ABBA deadlock between synchronous inode flushing in
> xfs_reclaim_inode and xfs_icluster_free. xfs_icluster_free locks the
> buffer, then takes inode ilocks, whilst synchronous reclaim takes
> the ilock followed by the buffer lock in xfs_iflush().
> 
> To avoid this deadlock, separate the inode cluster buffer locking
> semantics from the synchronous inode flush semantics, allowing
> callers to attempt to lock the buffer but still issue synchronous IO
> if it can get the buffer. This requires xfs_iflush() calls that
> currently use non-blocking semantics to pass SYNC_TRYLOCK rather
> than 0 as the flags parameter.
> 
> This allows xfs_reclaim_inode to avoid the deadlock on the buffer
> lock and detect the failure so that it can drop the inode ilock and
> restart the reclaim attempt on the inode. This allows
> xfs_ifree_cluster to obtain the inode lock, mark the inode stale and
> release it and hence defuse the deadlock situation. It also has the
> pleasant side effect of avoiding IO in xfs_reclaim_inode when it
> tries to next reclaim the inode as it is now marked stale.

Looks good.

Reviewed-by: Alex Elder <aelder@sgi.com>

> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>


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  reply	other threads:[~2011-03-25 20:57 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-03-23  6:14 xfs: outstanding patches for 2.6.39 Dave Chinner
2011-03-23  6:14 ` [PATCH 1/6] xfs: preallocation transactions do not need to be synchronous Dave Chinner
2011-03-24 17:18   ` brian.foster
2011-03-24 22:53     ` [PATCH V2] " Dave Chinner
2011-03-25 21:00   ` [PATCH 1/6] " Alex Elder
2011-03-25 22:02     ` Dave Chinner
2011-03-23  6:14 ` [PATCH 2/6] vmap: flush vmap aliases when mapping fails Dave Chinner
2011-03-25 21:00   ` Alex Elder
2011-03-23  6:14 ` [PATCH 3/6] xfs: introduce inode cluster buffer trylocks for xfs_iflush Dave Chinner
2011-03-25 21:00   ` Alex Elder [this message]
2011-03-23  6:14 ` [PATCH 4/6] xfs: xfs_trans_read_buf() should return an error on failure Dave Chinner
2011-03-23 11:53   ` Christoph Hellwig
2011-03-25 21:01   ` Alex Elder
2011-03-23  6:14 ` [PATCH 5/6] xfs: register the inode cache shrinker before quotachecks Dave Chinner
2011-03-23 21:24   ` Arkadiusz Miskiewicz
2011-03-25 12:56     ` Michael Weissenbacher
2011-03-25 23:08       ` Dave Chinner
2011-03-25 21:01   ` Alex Elder
2011-03-23  6:14 ` [PATCH 6/6] xfs: stop using the page cache to back the buffer cache Dave Chinner
2011-03-25 21:02   ` Alex Elder
2011-03-25 22:04     ` Dave Chinner
2011-03-23  7:01 ` xfs: outstanding patches for 2.6.39 Andi Kleen
2011-03-23 11:38   ` Dave Chinner
2011-03-23 16:05     ` Andi Kleen
2011-03-23 22:48       ` Dave Chinner
2011-03-23 11:18 ` Christoph Hellwig
2011-03-23 11:38   ` Dave Chinner

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